Plantronics CA12CD , Plantronics CA12CD-S Wireless Headset System Replacement/Spare Battery Pack.
Up to 8 hours of continuous talk time.
Charge one battery while remaining hands-free and mobile with another
Old part# 90225-01
note: when you first install this CA12CD battery, there will be a delay (up to 45 sec.). It's perfectly normal. The delay is caused when the remote unit looks for the best channel to link to and then cycles back to that channel. Typically, this should only take around 13 seconds.